Epitaxial Growth of the Diluted Magnetic Semiconductors CryGe1-y and CryMnxGe1-x-y

We report the epitaxial growth of CryGe1-y and CryMnxGe1-x-y(001) thin films on GaAs(001), describe the structural and transport properties, and compare the measured magnetic properties with those predicted by theory. The samples are strongly p-type, and hole densities increase with Cr concentration. The CryGe1-y system remains paramagnetic for the growth conditions and low Cr concentrations employed (y < 0.04), consistent with density functional theory predictions. Addition of Cr into the ferromagnetic semiconductor MnxGe1-x host systematically reduces the Curie temperature and total magnetization.